Effect of bake/cure temperature of an advanced organic ultra low-k material on the interface adhesion strength to metal barriers

Abstract

The interface adhesion strength of an advanced polymeric low-k material to different metal barriers was quantitatively measured using the four-point bending technique. Different sample configurations were tested in order to find the optimal configuration to study the polymer/barrier interface adhesion strength. The asymmetrical sample configuration with the notch at the film stack side was found to be the most suitable approach to study the adhesion strength of this interface. The effect of bake/cure temperature on the adhesion strength between polymer and barrier was investigated in more detail. Higher cure temperatures resulted in a lower amount of triple C-bonds in the polymer and lower polymer/barrier interface adhesion strength, while no differences in optical and mechanical properties were observed. Moreover, it was found that higher amount of Ta–C bonds formed at the interface improved the polymer/barrier interface adhesion, thereby suggesting that the chemical interaction between the polymer and metal barrier plays a major role in the adhesion performance.